In the present case the product can be converted to any state of aggregation, for example, to a liquid or molded article. The term “molded article” subsumes all possible articles produced from a natural or artificial base substance. This generally occurs by means of a molding die, with which the base substance is brought into a shape for the molded article. As an example, which is in no way restrictive or conclusive, viscose fibers are mentioned.
Viscose fibers are fibers consisting of the base material cellulose and are produced industrially via the viscose method. The chemical nature of viscose fibers is equivalent to that of cotton fibers.
Modal fibers are a product similar to viscose fibers. They also consist of 100% cellulose and, like viscose fibers, are produced from natural cellulose. Through a somewhat different process, however, higher fiber strength and improved fiber properties are achieved.
Tencel and lyocell fibers are also classified among the cellulose fibers. In the lyocell fibers the cellulose is dissolved directly and unchanged by the nontoxic solvent NMMO (N-methylmorpholine-N-oxide) without prior reaction with NaOH and derivatization to xanthate. Spinning of the lyocell fibers occurs in a dilute, aqueous NMMO bath, in which the solubility limit of cellulose is fallen short of and a fiber is formed on this account. For this purpose the corresponding spinning solution is forced through spinnerets. This lyocell method is described, for example, in DE 1 713 486, U.S. Pat. No. 3,447,939 or GB 8 216 566. Production of the appropriate spinning solution occurs in a horizontally operating kneading reactor, as shown in DE 198 37 210 or WO 02/20885 A1.
The spinning solution in these devices and according to the known methods is produced in the viscosity and corresponding cellulose concentration necessary for the subsequent spinning process. Corresponding devices for spinning, however, can only process a spinning solution with low viscosity, which, however, reduces the effectiveness of the process for production of the spinning solution. Very low viscosities and therefore low cellulose contents are necessary for special applications, in which the spinning solutions can no longer be effectively produced with the known technology.
A method of the aforementioned type is also known from WO 2009/098073, according to which the molding solution is diluted before the molding process. This means that the highly viscous spinning solution, whose viscosity lies above a viscosity that permits spinning, is temporarily stored, optionally heated and then brought to the viscosity of the desired molding solution in its own special reactor with a diluent.
The underlying task of the present invention is to simplify the aforementioned process and configure the corresponding production installation leaner.